全志平台boot里TVD倒车显示功能开发
2014-09-07 18:06
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倒车显示分两个部分，前端处理好视频输入信号，准备好内容，后端显示驱动再来把内容显示到LCD上。很明显，前端是TVD模块来处理的，后端是有DE模块来处理的，我们接下来先分析一下TVD模块怎么工作的。
首先，需要加载驱动打开设备驱动，如果有需要还可以执行IOCTL操作，跟在linux系统里操作驱动的IOCTL类似。代码如下：
/*****************************************************************************************************/
声明：本博内容均由http://blog.csdn.net/edsam49原创，转载请注明出处，谢谢！
/*****************************************************************************************************/
[plain]
view plaincopyprint?
ret = wBoot_driver_install("c:\\drv_tvd.drv");
if(ret != 0)
{
DMSG_PANIC("ERR: wBoot_driver_install drv_tvd driver failed\n");
return -1;
}
ret = wBoot_script_parser_fetch("tvin_para", "tvin_reverse_channel_num", &reverseChannel, 1);
if(ret)
{
__inf("unable to find tvin_para tvin_reverse_channel_num value\n");
}
__inf("BoardInit_TVD: reverseChannel=%x\n", reverseChannel);
TVDTransferToDRVInfo.ch = reverseChannel;
//open tvd devices , we transfer some TVD parameter to driver
tvd_hd = wBoot_driver_open(EGON2_EMOD_TYPE_DRV_TVD, &TVDTransferToDRVInfo);
if(tvd_hd == NULL)
{
DMSG_PANIC("ERR: open drv_tvd driver failed\n");
return -1;
}
加载驱动会执行到init接口，打开设备的时候会执行open接口，对应接口在上一篇文章中有介绍到。那么，我们可以再open的接口里对TVD 模块做一些必要的设置，当然一些模块的参数，我们可以再open的时候传给TVD的驱动，也就是传给DRV_TVD_OPEN函数接口。笔者根据需要传了一些控制参数进去，比如选择的TVD channel通道号，因为TVD有4个channel；显示的视频信号格式是NTSC信号还是PAL的信号，这样可以加快初始化，加快出正确的图像；以及Y/C的buffer地址，这里是为了让display这边方便的拿到显示buffer的地址，当然申请buffer放到TVD驱动里也是可以的，但是对应显示驱动就得晚于TVD驱动执行，这个问题其实也有人写一个固定的安全内存地址，其实也可以，只是感觉不灵活。
下面就说说TVD的具体驱动，首先TVD需要设置的是CLK，没有CLK什么都是扯，主要是ahb bus、tvd模块、DRAM、PLL3 VIDEO相关的clock，大致如下：
[objc]
view plaincopyprint?
ccm_clock_disable(TVD_CKID);
ccm_clock_enable(TVD_CKID);
set_wbit(CCM_DRAMCLK_GATE_CTRL, 0x1U<<4);//tvd
if(mode<4)
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x80105000);
put_wvalue(CCM_TVD_SCLK_CTRL,0x8000800a);
}
else
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x8010905a);
put_wvalue(CCM_TVD_SCLK_CTRL,0x80008004);
}
void ccm_clock_enable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
set_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
set_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
set_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
set_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
set_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}
void ccm_clock_disable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
clr_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
clr_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
clr_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
clr_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
clr_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}
接着就是控制TVD模块具体的寄存器了，使能必不可少，IRQ设置不可少，对比度、亮度、饱和度等，当然还有其他的一堆，初步的值是全志提供的，但是为了更好的显示效果，主要是匹配你这个产品的屏参吧，那我们就看一段NTSC的参数吧！
[objc]
view plaincopyprint?
put_wvalue( TVD_BASE + 0x0008, 0x00590900); //notch width 0059_0100
put_wvalue( TVD_BASE + 0x000c, 0x00000010); //YC sep
put_wvalue( TVD_BASE + 0x0010, 0x008A32DD); //sync height
put_wvalue( TVD_BASE + 0x0014, 0x800000a0); //adjust YC delay
put_wvalue( TVD_BASE + 0x0018, 0x00002080); //adjust luma brightness
put_wvalue( TVD_BASE + 0x001c, 0x008a0080); //chroma AGC target
put_wvalue( TVD_BASE + 0x0024, 0x0682810a); //DISABLE AGC GATE KILL!!!!!!!!!!!!!!!!!
put_wvalue( TVD_BASE + 0x0028, 0x00006440); //0000_6440 0000_5838
put_wvalue( TVD_BASE + 0x0034, 0x20000000); //2000_0000 2400_0000
put_wvalue( TVD_BASE + 0x0044, 0x50824632); //burst gate
put_wvalue( TVD_BASE + 0x004c, 0x0e70106c); //NO CLAMP DURING VSYNC!!!!!!!!!!!!!!!!!
put_wvalue( TVD_BASE + 0x0054, 0x00000025); //peak en
put_wvalue( TVD_BASE + 0x006c, 0x00fffa0a); //YC separation config
put_wvalue( TVD_BASE + 0x0080, 0x00500082); //hactive start and width
put_wvalue( TVD_BASE + 0x0084, 0x00610022); //vactive start and height
put_wvalue( TVD_BASE + 0x0030, 0x21f07c1f); //21f0_7c1f 262E_8BA2
put_wvalue( TVD_BASE + 0x002c, 0x0000CB74);
put_wvalue( TVD_BASE + 0x0074, 0x000003c3); //chroma edge enhance
put_wvalue( TVD_BASE + 0x050c, 0x0000000b);
put_wvalue( TVD_BASE + 0x051c, 0x00100000);
put_wvalue( TVD_BASE + 0x0134 + ch * 0x100, y<<16 | x);
put_wvalue( TVD_BASE + 0x0138 + ch * 0x100, len);
put_wvalue( TVD_BASE + 0x0100 + ch * 0x100, addr0);
put_wvalue( TVD_BASE + 0x0110 + ch * 0x100, addr1);
put_wvalue( TVD_BASE + 0x0104 + ch * 0x100, addr2);
put_wvalue( TVD_BASE + 0x0114 + ch * 0x100, addr3);
put_wvalue( TVD_BASE + 0x0108 + ch * 0x100, addr4);
put_wvalue( TVD_BASE + 0x0118 + ch * 0x100, addr5);
put_wvalue( TVD_BASE + 0x010c + ch * 0x100, addr6);
put_wvalue( TVD_BASE + 0x011c + ch * 0x100, addr7);
put_wvalue( TVD_BASE + 0x0130 + ch * 0x100, frame<<26 | is_mb<<24 | \ hsample<<12 | is_yuv422<<4 | 0x1);
put_wvalue(TVD_BASE+0x0148,0xf1ffffff);//int//int en//frame end, overflow, underflow
put_wvalue(TVD_BASE+0x0140,0xffffffff);//clear irq//frame end, overflow, underflow
put_wvalue(TVD_BASE+0x014c,0xffffffff);//address change error
put_wvalue(TVD_BASE+0x0150,0x00000000);//int en//lock unlock
put_wvalue(TVD_BASE+0x0154,0x0000ffff);//clear irq//lock unlock
这些程序一走，数据就差不多出来了。那么接下来就准备显示吧！
显示这部分在boot里面也已经是支持了的，但是需要自己去改造成自己需要的。首先模块的初始化还是借用boot里面已经支持的BoardInit_Display（）接口，除此之前就需要自己动手来做了。比如要设置显示layer具体参数，比如显示的宽高、buffer的地址、显示的格式、是否是UV combined模式等，也不少。除此之外还得打开layer，因为申请layer已经在BoardInit_Display（）接口里完成了。笔者的NTSC的显示参数大致如下：
[objc]
view plaincopyprint?
memset((&layer_para), 0, sizeof(layer_para));
layer_para.fb.size.width = 704;
layer_para.fb.size.height = 480;
layer_para.fb.addr[0] = (__u32)TVDTransferToDRVInfo.addrYx;//TVD_ADDR_Y0;
layer_para.fb.addr[1] = (__u32)TVDTransferToDRVInfo.addrCx;//TVD_ADDR_C0;
layer_para.fb.mode = DISP_MOD_NON_MB_UV_COMBINED;
layer_para.fb.format = DISP_FORMAT_YUV422;
layer_para.fb.br_swap = 0;
layer_para.fb.seq = DISP_SEQ_UYVY;
layer_para.ck_enable = 0;
layer_para.mode = DISP_LAYER_WORK_MODE_SCALER;
layer_para.alpha_en = 1;
layer_para.alpha_val = 0xff;
layer_para.pipe = 0;
layer_para.src_win.x = 15;
layer_para.src_win.y = 10;
layer_para.src_win.width = 688;
layer_para.src_win.height = 470;
layer_para.scn_win.x = 0;
layer_para.scn_win.y = 0;
layer_para.scn_win.width = De_GetSceenWidth();
layer_para.scn_win.height = De_GetSceenHeight();
通过以上的简单分析，倒车显示是基本OK了。但是记得退出倒车的时候要关闭显示，关闭TVD，卸载对应驱动。到此，基本上整个过程就分析完了。
首先，需要加载驱动打开设备驱动，如果有需要还可以执行IOCTL操作，跟在linux系统里操作驱动的IOCTL类似。代码如下：
/*****************************************************************************************************/
声明：本博内容均由http://blog.csdn.net/edsam49原创，转载请注明出处，谢谢！
/*****************************************************************************************************/
[plain]
view plaincopyprint?
ret = wBoot_driver_install("c:\\drv_tvd.drv");
if(ret != 0)
{
DMSG_PANIC("ERR: wBoot_driver_install drv_tvd driver failed\n");
return -1;
}
ret = wBoot_script_parser_fetch("tvin_para", "tvin_reverse_channel_num", &reverseChannel, 1);
if(ret)
{
__inf("unable to find tvin_para tvin_reverse_channel_num value\n");
}
__inf("BoardInit_TVD: reverseChannel=%x\n", reverseChannel);
TVDTransferToDRVInfo.ch = reverseChannel;
//open tvd devices , we transfer some TVD parameter to driver
tvd_hd = wBoot_driver_open(EGON2_EMOD_TYPE_DRV_TVD, &TVDTransferToDRVInfo);
if(tvd_hd == NULL)
{
DMSG_PANIC("ERR: open drv_tvd driver failed\n");
return -1;
}
ret = wBoot_driver_install("c:\\drv_tvd.drv");
if(ret != 0)
{
DMSG_PANIC("ERR: wBoot_driver_install drv_tvd driver failed\n");
return -1;
}
ret = wBoot_script_parser_fetch("tvin_para", "tvin_reverse_channel_num", &reverseChannel, 1);
if(ret)
{
__inf("unable to find tvin_para tvin_reverse_channel_num value\n");
}
__inf("BoardInit_TVD: reverseChannel=%x\n", reverseChannel);
TVDTransferToDRVInfo.ch = reverseChannel;
//open tvd devices , we transfer some TVD parameter to driver
tvd_hd = wBoot_driver_open(EGON2_EMOD_TYPE_DRV_TVD, &TVDTransferToDRVInfo);
if(tvd_hd == NULL)
{
DMSG_PANIC("ERR: open drv_tvd driver failed\n");
return -1;
}加载驱动会执行到init接口，打开设备的时候会执行open接口，对应接口在上一篇文章中有介绍到。那么，我们可以再open的接口里对TVD 模块做一些必要的设置，当然一些模块的参数，我们可以再open的时候传给TVD的驱动，也就是传给DRV_TVD_OPEN函数接口。笔者根据需要传了一些控制参数进去，比如选择的TVD channel通道号，因为TVD有4个channel；显示的视频信号格式是NTSC信号还是PAL的信号，这样可以加快初始化，加快出正确的图像；以及Y/C的buffer地址，这里是为了让display这边方便的拿到显示buffer的地址，当然申请buffer放到TVD驱动里也是可以的，但是对应显示驱动就得晚于TVD驱动执行，这个问题其实也有人写一个固定的安全内存地址，其实也可以，只是感觉不灵活。
下面就说说TVD的具体驱动，首先TVD需要设置的是CLK，没有CLK什么都是扯，主要是ahb bus、tvd模块、DRAM、PLL3 VIDEO相关的clock，大致如下：
[objc]
view plaincopyprint?
ccm_clock_disable(TVD_CKID);
ccm_clock_enable(TVD_CKID);
set_wbit(CCM_DRAMCLK_GATE_CTRL, 0x1U<<4);//tvd
if(mode<4)
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x80105000);
put_wvalue(CCM_TVD_SCLK_CTRL,0x8000800a);
}
else
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x8010905a);
put_wvalue(CCM_TVD_SCLK_CTRL,0x80008004);
}
void ccm_clock_enable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
set_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
set_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
set_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
set_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
set_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}
void ccm_clock_disable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
clr_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
clr_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
clr_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
clr_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
clr_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}
ccm_clock_disable(TVD_CKID);
ccm_clock_enable(TVD_CKID);
set_wbit(CCM_DRAMCLK_GATE_CTRL, 0x1U<<4);//tvd
if(mode<4)
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x80105000);
put_wvalue(CCM_TVD_SCLK_CTRL,0x8000800a);
}
else
{
put_wvalue(CCM_PLL3_VIDEO_CTRL,0x8010905a);
put_wvalue(CCM_TVD_SCLK_CTRL,0x80008004);
}
void ccm_clock_enable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
set_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
set_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
set_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
set_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
set_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}
void ccm_clock_disable(u32 clk_id)
{
switch(clk_id>>8) {
case AXI_BUS:
clr_wbit(CCM_AXI_GATE_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS0:
clr_wbit(CCM_AHB_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case AHB_BUS1:
clr_wbit(CCM_AHB_GATE1_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB0_BUS0:
clr_wbit(CCM_APB0_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
case APB1_BUS0:
clr_wbit(CCM_APB1_GATE0_CTRL, 0x1U<<(clk_id&0xff));
break;
}
}接着就是控制TVD模块具体的寄存器了，使能必不可少，IRQ设置不可少，对比度、亮度、饱和度等，当然还有其他的一堆，初步的值是全志提供的，但是为了更好的显示效果，主要是匹配你这个产品的屏参吧，那我们就看一段NTSC的参数吧！
[objc]
view plaincopyprint?
put_wvalue( TVD_BASE + 0x0008, 0x00590900); //notch width 0059_0100
put_wvalue( TVD_BASE + 0x000c, 0x00000010); //YC sep
put_wvalue( TVD_BASE + 0x0010, 0x008A32DD); //sync height
put_wvalue( TVD_BASE + 0x0014, 0x800000a0); //adjust YC delay
put_wvalue( TVD_BASE + 0x0018, 0x00002080); //adjust luma brightness
put_wvalue( TVD_BASE + 0x001c, 0x008a0080); //chroma AGC target
put_wvalue( TVD_BASE + 0x0024, 0x0682810a); //DISABLE AGC GATE KILL!!!!!!!!!!!!!!!!!
put_wvalue( TVD_BASE + 0x0028, 0x00006440); //0000_6440 0000_5838
put_wvalue( TVD_BASE + 0x0034, 0x20000000); //2000_0000 2400_0000
put_wvalue( TVD_BASE + 0x0044, 0x50824632); //burst gate
put_wvalue( TVD_BASE + 0x004c, 0x0e70106c); //NO CLAMP DURING VSYNC!!!!!!!!!!!!!!!!!
put_wvalue( TVD_BASE + 0x0054, 0x00000025); //peak en
put_wvalue( TVD_BASE + 0x006c, 0x00fffa0a); //YC separation config
put_wvalue( TVD_BASE + 0x0080, 0x00500082); //hactive start and width
put_wvalue( TVD_BASE + 0x0084, 0x00610022); //vactive start and height
put_wvalue( TVD_BASE + 0x0030, 0x21f07c1f); //21f0_7c1f 262E_8BA2
put_wvalue( TVD_BASE + 0x002c, 0x0000CB74);
put_wvalue( TVD_BASE + 0x0074, 0x000003c3); //chroma edge enhance
put_wvalue( TVD_BASE + 0x050c, 0x0000000b);
put_wvalue( TVD_BASE + 0x051c, 0x00100000);
put_wvalue( TVD_BASE + 0x0134 + ch * 0x100, y<<16 | x);
put_wvalue( TVD_BASE + 0x0138 + ch * 0x100, len);
put_wvalue( TVD_BASE + 0x0100 + ch * 0x100, addr0);
put_wvalue( TVD_BASE + 0x0110 + ch * 0x100, addr1);
put_wvalue( TVD_BASE + 0x0104 + ch * 0x100, addr2);
put_wvalue( TVD_BASE + 0x0114 + ch * 0x100, addr3);
put_wvalue( TVD_BASE + 0x0108 + ch * 0x100, addr4);
put_wvalue( TVD_BASE + 0x0118 + ch * 0x100, addr5);
put_wvalue( TVD_BASE + 0x010c + ch * 0x100, addr6);
put_wvalue( TVD_BASE + 0x011c + ch * 0x100, addr7);
put_wvalue( TVD_BASE + 0x0130 + ch * 0x100, frame<<26 | is_mb<<24 | \ hsample<<12 | is_yuv422<<4 | 0x1);
put_wvalue(TVD_BASE+0x0148,0xf1ffffff);//int//int en//frame end, overflow, underflow
put_wvalue(TVD_BASE+0x0140,0xffffffff);//clear irq//frame end, overflow, underflow
put_wvalue(TVD_BASE+0x014c,0xffffffff);//address change error
put_wvalue(TVD_BASE+0x0150,0x00000000);//int en//lock unlock
put_wvalue(TVD_BASE+0x0154,0x0000ffff);//clear irq//lock unlock
put_wvalue( TVD_BASE + 0x0008, 0x00590900); //notch width 0059_0100 put_wvalue( TVD_BASE + 0x000c, 0x00000010); //YC sep put_wvalue( TVD_BASE + 0x0010, 0x008A32DD); //sync height put_wvalue( TVD_BASE + 0x0014, 0x800000a0); //adjust YC delay put_wvalue( TVD_BASE + 0x0018, 0x00002080); //adjust luma brightness put_wvalue( TVD_BASE + 0x001c, 0x008a0080); //chroma AGC target put_wvalue( TVD_BASE + 0x0024, 0x0682810a); //DISABLE AGC GATE KILL!!!!!!!!!!!!!!!!! put_wvalue( TVD_BASE + 0x0028, 0x00006440); //0000_6440 0000_5838 put_wvalue( TVD_BASE + 0x0034, 0x20000000); //2000_0000 2400_0000 put_wvalue( TVD_BASE + 0x0044, 0x50824632); //burst gate put_wvalue( TVD_BASE + 0x004c, 0x0e70106c); //NO CLAMP DURING VSYNC!!!!!!!!!!!!!!!!! put_wvalue( TVD_BASE + 0x0054, 0x00000025); //peak en put_wvalue( TVD_BASE + 0x006c, 0x00fffa0a); //YC separation config put_wvalue( TVD_BASE + 0x0080, 0x00500082); //hactive start and width put_wvalue( TVD_BASE + 0x0084, 0x00610022); //vactive start and height put_wvalue( TVD_BASE + 0x0030, 0x21f07c1f); //21f0_7c1f 262E_8BA2 put_wvalue( TVD_BASE + 0x002c, 0x0000CB74); put_wvalue( TVD_BASE + 0x0074, 0x000003c3); //chroma edge enhance put_wvalue( TVD_BASE + 0x050c, 0x0000000b); put_wvalue( TVD_BASE + 0x051c, 0x00100000); put_wvalue( TVD_BASE + 0x0134 + ch * 0x100, y<<16 | x); put_wvalue( TVD_BASE + 0x0138 + ch * 0x100, len); put_wvalue( TVD_BASE + 0x0100 + ch * 0x100, addr0); put_wvalue( TVD_BASE + 0x0110 + ch * 0x100, addr1); put_wvalue( TVD_BASE + 0x0104 + ch * 0x100, addr2); put_wvalue( TVD_BASE + 0x0114 + ch * 0x100, addr3); put_wvalue( TVD_BASE + 0x0108 + ch * 0x100, addr4); put_wvalue( TVD_BASE + 0x0118 + ch * 0x100, addr5); put_wvalue( TVD_BASE + 0x010c + ch * 0x100, addr6); put_wvalue( TVD_BASE + 0x011c + ch * 0x100, addr7); put_wvalue( TVD_BASE + 0x0130 + ch * 0x100, frame<<26 | is_mb<<24 | \ hsample<<12 | is_yuv422<<4 | 0x1); put_wvalue(TVD_BASE+0x0148,0xf1ffffff);//int//int en//frame end, overflow, underflow put_wvalue(TVD_BASE+0x0140,0xffffffff);//clear irq//frame end, overflow, underflow put_wvalue(TVD_BASE+0x014c,0xffffffff);//address change error put_wvalue(TVD_BASE+0x0150,0x00000000);//int en//lock unlock put_wvalue(TVD_BASE+0x0154,0x0000ffff);//clear irq//lock unlock
这些程序一走，数据就差不多出来了。那么接下来就准备显示吧！
显示这部分在boot里面也已经是支持了的，但是需要自己去改造成自己需要的。首先模块的初始化还是借用boot里面已经支持的BoardInit_Display（）接口，除此之前就需要自己动手来做了。比如要设置显示layer具体参数，比如显示的宽高、buffer的地址、显示的格式、是否是UV combined模式等，也不少。除此之外还得打开layer，因为申请layer已经在BoardInit_Display（）接口里完成了。笔者的NTSC的显示参数大致如下：
[objc]
view plaincopyprint?
memset((&layer_para), 0, sizeof(layer_para));
layer_para.fb.size.width = 704;
layer_para.fb.size.height = 480;
layer_para.fb.addr[0] = (__u32)TVDTransferToDRVInfo.addrYx;//TVD_ADDR_Y0;
layer_para.fb.addr[1] = (__u32)TVDTransferToDRVInfo.addrCx;//TVD_ADDR_C0;
layer_para.fb.mode = DISP_MOD_NON_MB_UV_COMBINED;
layer_para.fb.format = DISP_FORMAT_YUV422;
layer_para.fb.br_swap = 0;
layer_para.fb.seq = DISP_SEQ_UYVY;
layer_para.ck_enable = 0;
layer_para.mode = DISP_LAYER_WORK_MODE_SCALER;
layer_para.alpha_en = 1;
layer_para.alpha_val = 0xff;
layer_para.pipe = 0;
layer_para.src_win.x = 15;
layer_para.src_win.y = 10;
layer_para.src_win.width = 688;
layer_para.src_win.height = 470;
layer_para.scn_win.x = 0;
layer_para.scn_win.y = 0;
layer_para.scn_win.width = De_GetSceenWidth();
layer_para.scn_win.height = De_GetSceenHeight();
memset((&layer_para), 0, sizeof(layer_para)); layer_para.fb.size.width = 704; layer_para.fb.size.height = 480; layer_para.fb.addr[0] = (__u32)TVDTransferToDRVInfo.addrYx;//TVD_ADDR_Y0; layer_para.fb.addr[1] = (__u32)TVDTransferToDRVInfo.addrCx;//TVD_ADDR_C0; layer_para.fb.mode = DISP_MOD_NON_MB_UV_COMBINED; layer_para.fb.format = DISP_FORMAT_YUV422; layer_para.fb.br_swap = 0; layer_para.fb.seq = DISP_SEQ_UYVY; layer_para.ck_enable = 0; layer_para.mode = DISP_LAYER_WORK_MODE_SCALER; layer_para.alpha_en = 1; layer_para.alpha_val = 0xff; layer_para.pipe = 0; layer_para.src_win.x = 15; layer_para.src_win.y = 10; layer_para.src_win.width = 688; layer_para.src_win.height = 470; layer_para.scn_win.x = 0; layer_para.scn_win.y = 0; layer_para.scn_win.width = De_GetSceenWidth(); layer_para.scn_win.height = De_GetSceenHeight();
通过以上的简单分析，倒车显示是基本OK了。但是记得退出倒车的时候要关闭显示，关闭TVD，卸载对应驱动。到此，基本上整个过程就分析完了。
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